Disler D G, Peters T L, Muscoreil S J, Ratner L M, Wagle W A, Cousins J P, Rifkin M D
Department of Radiology, Albany Medical College, NY 12208.
AJR Am J Roentgenol. 1994 Oct;163(4):887-92. doi: 10.2214/ajr.163.4.8092029.
We studied healthy volunteers with fat-suppressed three-dimensional (3D) spoiled gradient-recalled acquisition in the steady state (SPGR) to determine parameters that maximize positive contrast between knee articular cartilage and fluid, marrow fat, and muscle; and we compared the technique with conventional MR imaging sequences. The purpose was to determine if fat-suppressed 3D SPGR imaging is useful for detecting abnormalities of the articular cartilages.
The knees of 10 healthy volunteers were imaged in the axial plane. Fat-suppressed 3D SPGR imaging was performed with a TR of 60 msec, a TE ranging from 5 to 15 msec, and a flip angle ranging from 20 degrees to 80 degrees. This was followed by a similar set of fat-suppressed two-dimensional (2D) SPGR images, and conventional T1- and T2-weighted spin-echo and multiplanar gradient studies. Contrast-to-noise (C/N) ratios were determined for cartilage versus a saline fluid phantom, marrow fat, and muscle. Optimal parameters were determined both quantitatively and by a blinded subjective analysis.
A TE of 5 msec and a flip angle of 40 degrees demonstrated the greatest C/N ratio between the signals for cartilage and for fluid, marrow, and muscle. C/N ratios in the 3D sequences were higher than in the 2D, spin-echo, and gradient series, although the absolute C/N ratio values for the T2-weighted spin-echo sequence were higher than those for the 3D fat-suppressed SPGR sequence. Subjective analysis showed articular cartilage to have a consistent trilaminar appearance, and independent interpreters favored a 3D fat-suppressed SPGR sequence with a TE of 5 msec and a flip angle of 40 degrees. Three subjects with incidental joint fluid had C/N ratios within a 95% confidence range for cartilage versus the fluid phantom.
When a fat-suppressed 3D SPGR sequence of 60/5/40 degrees (TR/TE/flip angle) is used, MR images can show high positive contrast between articular hyaline cartilage and adjacent structures. This convenient technique is different from standard MR imaging sequences because it demonstrates greater signal intensity in cartilage than in fluid, marrow fat, and muscle, and because it consistently shows an organized internal architecture of hyaline cartilage. Fat-suppressed 3D SPGR imaging therefore has promise for detecting abnormalities of the articular cartilage.
我们对健康志愿者进行了脂肪抑制三维（3D）稳态扰相梯度回波序列（SPGR）检查，以确定能使膝关节软骨与液体、骨髓脂肪及肌肉之间的正性对比最大化的参数；并将该技术与传统磁共振成像序列进行比较。目的是确定脂肪抑制3D SPGR成像是否有助于检测关节软骨异常。
对10名健康志愿者的膝关节进行轴位成像。采用重复时间（TR）为60毫秒、回波时间（TE）为5至15毫秒、翻转角为20度至80度的条件进行脂肪抑制3D SPGR成像。随后进行一组类似的脂肪抑制二维（2D）SPGR图像以及传统的T1加权和T2加权自旋回波序列及多平面梯度序列检查。测定软骨与生理盐水模拟物、骨髓脂肪及肌肉之间的对比噪声（C/N）比。通过定量分析及盲法主观分析确定最佳参数。
TE为5毫秒、翻转角为40度时，软骨与液体、骨髓及肌肉信号之间的C/N比最大。3D序列中的C/N比高于2D、自旋回波及梯度序列，尽管T2加权自旋回波序列的绝对C/N比值高于3D脂肪抑制SPGR序列。主观分析显示关节软骨呈现一致的三层外观，独立的解读人员更倾向于采用TE为5毫秒、翻转角为40度的3D脂肪抑制SPGR序列。3名有偶然关节积液的受试者，软骨与液体模拟物之间的C/N比在95%置信范围内。
当采用60/5/40度（TR/TE/翻转角）的脂肪抑制3D SPGR序列时，磁共振图像可显示关节透明软骨与相邻结构之间的高正性对比。这种便捷技术不同于标准磁共振成像序列，因为它在软骨中显示的信号强度高于液体、骨髓脂肪及肌肉，且能始终显示透明软骨有组织的内部结构。因此，脂肪抑制3D SPGR成像有望用于检测关节软骨异常。
